JPH1116454A - Manufacture of contact material for vacuum valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of especially restrike of an arc in voltage resistant characteristics and to reduce the dispersion of a contact material by melting a conducting component containing Cu and an arc resistant component containing at least one of Cr, V, W, Mo, Ta, Nb, and Fe within the range of the melting point of both components, then casting. SOLUTION: A conducting component of a main contact material for constituting one or both contacts fixed to a moving electrode and a fixed electrode is preferably limited to 40-90 vol.%. Since the bonding strength between the conducting component and an arc resistant component is strong, irregularity formed by minor welding on the surface of the contact and release of fine particles caused by the local coming off of the arc resistant component are reduced, and restrike is suppressed. By the melting and casting both components, micro contact structure is formed and the dispersion of restrike generation is suppressed. Preferably, by using the arc resistant material having a mean particle size of 1-10 μm, uniform melting and distribution into the conducting component are obtained. Adding of a low melting point element such as Bi, In, and Sn, and a light element such as B, C to the components is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a contact material for a vacuum valve having improved withstand voltage characteristics.

[0002]

2. Description of the Related Art The characteristics required for a contact material for a vacuum valve include three basic requirements for welding resistance, withstand voltage, and breaking, and in addition to the above, the temperature rise and contact resistance are low and stable. Is an important requirement.

[0003] However, among these requirements,
Due to conflicts, it is not possible to satisfy all requirements with a single metal species. For this reason, in many contact materials that have been put into practical use, two or more types of elements that can mutually compensate for the insufficient performance are combined and suitable for a specific application such as for large current or high voltage. Contact materials for vacuum valves have been developed, and materials with excellent properties have been developed.However, contact materials for vacuum valves that sufficiently satisfy the demands for higher voltage and larger current interruption have not yet been obtained. There is no fact.

For example, a CuBi contact material (Japanese Patent Publication No. 41-121) is used as a contact material having improved current resistance and improved welding resistance.
No. 31), CuTe contact (JP-B No. 44-233751)
It has been known. Also, a CuCr contact is known as a contact aimed at increasing the current and increasing the breakdown voltage (Japanese Patent Publication No. 45-45).
35101). Also, a CuCrBi contact is known as a contact having improved resistance to welding of a CuCr contact (Japanese Patent Publication No. Sho 6 (1988)).
1-41091). However, although a contact material having excellent characteristics has been developed, a contact material that sufficiently satisfies the demands for higher withstand voltage, especially suppression of the frequency of restriking and interruption of large current, has been obtained. There is no actual situation.

[0005]

As described above, there is a problem that it is necessary to provide a contact material in which withstand voltage characteristics, in particular, occurrence of restriking is suppressed and the variation thereof is reduced.

[0006] The present invention relates to a contact material for a vacuum valve, and in particular, to provide a method for producing a contact material for a vacuum valve with less variation in withstand voltage characteristics without lowering the withstand voltage characteristics. .

[0007]

The method for producing a contact material for a vacuum valve of the present invention uses the following means to solve the above-mentioned problems: (1) a conductive component containing Cu and Cr ( Chrome), V
(Vanadium), W (tungsten), Mo (molybdenum), Ta (tantalum), Nb (niobium), Fe
It is obtained by melting a contact material containing at least one or more arc-resistant components of (iron) within a range from the melting point of the conductive component to the melting point of the arc-resistant component, and then casting. Manufacturing method of contact material for vacuum valve.

(2) The method according to claim 1, wherein the conductive component is 40 to 90% by volume.

(3) The arc resistant component raw material has an average particle size of 1 μm.
A method for producing a contact material for a vacuum valve, comprising a powder or granules of -10 mm.

(4) At least I type of Bi (bismuth), In (indium), Sn (tin), Te (tellurium) and Pb (lead) is added in an amount of 0.05 to 3% by volume. A method for producing a contact material for a vacuum valve, characterized by melting.

(5) B (boron), C (carbon), Ti
(Titanium), Zr (zirconium), Y (yttrium), Al (aluminum)
5. The method for producing a contact material for a vacuum valve according to claim 1, wherein 0.01% to 5% by volume of at least one kind is added and dissolved.

(6) The mold is made of Cu, Cu alloy, Fe, F
A method for manufacturing a contact material family for a vacuum valve, comprising at least one of e-alloys.

(7) The mold depth L is 1.5 times the mold diameter D.
A method for producing a contact material for a vacuum valve, wherein the method is at least twice as large.

(8) A method of manufacturing a contact material for a vacuum valve, wherein the mold has a plurality of through holes on a side surface.

(9) A method for manufacturing a contact material for a vacuum valve, wherein the melting method is a vacuum melting method or a continuous casting method.

Is a means for solving the problem.

The occurrence of restriking in a vacuum valve has been regarded as a problem for a long time, and its cause has not been elucidated. However, the main factors are emission of fine particles from the contact surface and sudden occurrence. Outgassing is considered. Regarding the latter, trial manufacture evaluation is being conducted in the direction of reducing the gas content in the contact.

On the other hand, it is presumed that the release of the fine particles from the contact surface is due to irregularities formed on the contact surface caused by fine welding or the like and local dropout of the arc resistant component. As a method for improving this, for example, a method of strengthening the adhesion strength between the conductive component and the arc-resistant component has been devised.

Another problem is the variation in the occurrence of restriking. As a cause of this, there is a problem of non-uniformity of the contact microstructure. For this reason, for example, it has been attempted to manufacture contacts by powder metallurgy using fine arc-resistant component raw materials on the order of several microns. .

However, when this method is used, the problem that the gas content is increased and the withstand voltage characteristic is reduced remains. Therefore, this problem was solved by melting and agglomerating the arc-resistant component and the conductive component to obtain a more microscopic contact structure.

Further, in such a composition system, in order to achieve a remarkable improvement in the yield which is significantly deteriorated, the present invention was achieved by adding an arc-resistant component raw material and a third element, and devising the shape of the mold material.

First, the material of the arc resistant component is set to 1 μm to 10 mm.
By doing so, uniform dissolution and distribution in the conductive component were made possible. Further, by adding a low-melting element such as Bi, In, or Sn, the arc-resistant components are prevented from adhering to each other during heating in a solid state. Further, by adding light elements such as B and C, the reliability was further improved. In addition, the mold was cooled smoothly and a special mold shape was used to eliminate residual gas.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for producing a contact material for a vacuum valve according to the present invention will be described. First, the configuration of a vacuum valve to which the contact material of the present invention is applied will be described with reference to FIGS.

FIG. 1 shows an example of the construction of a vacuum valve to which the contact material of the present invention is applied. In FIG. 1, reference numeral 1 denotes a shut-off chamber, and this shut-off chamber 1 is formed of an insulating material in a substantially cylindrical shape. The insulating container 2 and the metallic lids 4a and 4b provided at both ends thereof with sealing metal fittings 3a and 3b are formed in a vacuum-tight manner.

Thus, a pair of electrodes 7 and 8 attached to the opposite ends of the conductive rods 5 and 6 are provided in the cut-off chamber 1, and the upper electrode 7 is fixed and the lower electrode 8 is It is a movable electrode. A bellows 9 is attached to the conductive rod 6 of the movable electrode 8 to enable the electrode 8 to move in the axial direction while maintaining the inside of the shut-off chamber 1 in a vacuum-tight manner. A metallic arc shield 10 is provided to prevent the bellows 9 from being covered with arc vapor.

Reference numeral 11 denotes a metallic arc shield provided in the cut-off chamber 1 so as to cover the electrodes 7 and 8;
Is prevented from being covered with arc vapor. further,
2, the electrode 8 is fixed to the conductive rod 6 by a brazing portion 12, or is crimp-connected by caulking. The contact 13a is soldered 1 to the electrode 8.
4 is fixed. Note that 13b in FIG. 1 is a fixed-side contact.

The contact material according to the present invention is suitable for forming both or any one of the above-mentioned contacts 13a and 13b. Next, a method for evaluating each contact will be described.

The arc resistance characteristics were obtained by processing a contact having a diameter of 45 mm into a predetermined shape, assembling the same into a predetermined vacuum valve, and evaluating a re-ignition occurrence rate by an advanced small current test. Current is 500A
And the recovery voltage is 12.5 kV. Number of tests is 2
000 times. The average value of the CuCr contacts manufactured by the infiltration method shown in Comparative Example 1 described below is set to 1.0, and the relative values are described together with the dispersion of the five valves.

(Comparative Example 1) A Cr powder having an average particle diameter of 100 µm was filled in a carbon crucible, and then temporarily sintered in a vacuum atmosphere of 10 ^-2 Pa (Pascal) under the sintering conditions of 1150 ° C for 1 hour. A Cr skeleton was obtained. After that, oxygen-free copper was replaced with Cr.
Placed on the skeleton and in a similar vacuum atmosphere, 113
Infiltrate under 0 ° C x 0.5 hour infiltration condition, 50% by volume
A CrCu contact was obtained. After processing into a predetermined shape, a test of the static withstand voltage characteristic and the breaking performance of the withstand voltage test are performed, and this characteristic value is used as a reference value of a contact which is to be prototyped and evaluated in the future.

(Comparative Example 2, Examples 1-4, Comparative Example 3) 2
Cr briquettes and oxygen-free copper pulverized to about 0 mm were used as raw materials and melted in a vacuum atmosphere. After heating to at least the melting point of Cu to dissolve at least a portion of Cr, high purity Ar
(Argon) was sealed at a point of 150 Torr and cast into a cast iron mold. CuCr ingots with different amounts of Cr added were manufactured by this method, and the Cu amounts were 20, 40, and 5, respectively.
Samples of 0, 70, 90, and 98% by volume were extracted (Comparative Example 2, Examples 1, 2, 3, 4, and Comparative Example 3, respectively). The re-ignition frequency was measured by a predetermined method.

As shown in Table 1, it was found that the contact manufactured by the melting method had smaller variation than the contact manufactured by the infiltration method. However, in the case of CuCr-based contact materials,
If the Cr content is too small or too large, the average re-ignition incidence tends to increase. In the former, it is considered that the withstand voltage characteristics of the contact self-sustaining are reduced, and in the latter, the aggregation of Cr is excessively advanced.

[0032]

[Table 1] (Examples 5, 6, 7, 8 and Comparative Example 4) In a Cu liquid phase melted in a vacuum, average particle diameters were 1 μm and 100 μm, respectively.
m, 1 mm of Mo powder, and a lump of Mo lump crushed to 10 mm and 50 mm were added and dissolved for a while.
rr was sealed and cast into a cast iron mold (Examples 5 and 5 respectively).
6, 7, 8, Comparative Example 4).

When the ingot was cut in the longitudinal direction and the cross-sectional macrostructure was observed, the average grain size of Mo was 1 μm, 1
The sample of 00 μm and 1 mm had an overall uniform composition, but in Comparative Example 4 to which 50 mm of Mo was added,
However, segregation was remarkable in a state where it could not be melted. In Example 8 in which Mo having an average particle size of 10 mm was added, segregation was also observed, but the central portion of the ingot was usable. From these ingots, contacts were made from any part and the incidence of restriking was investigated. Similar to the macrostructure of the ingot, those with less segregation had less variation,
The contact with large segregation had large variations.

[0034]

[Table 2] (Comparative Example 5, Examples 9, 10, 11, and Comparative Example 6) W powder having an average particle size of 5 μm and oxygen-free copper were dissolved and cast and melted under the same conditions as in Example 1 (Comparative Example 5).

Further, Bi is 0.05% and In is 0.5%.
%, 1% of Sn, 2% of Te, and 10% of Pb, and then dissolved (Examples 9, 10, 11, and Comparative Example 6).

When cut along the longitudinal direction and the macrostructure was observed, Comparative Example 5 without the addition of the third element showed remarkable agglomeration of W, whereas Examples 9 and 1 with the addition of Bi, Te, etc.
0, 11 and Comparative Example 6 had little segregation. This is probably because the sintering of W progressed before the melting temperature, and the W could not be dispersed in the Cu liquid phase. On the other hand, it is considered that the dispersion of W in the material to which Bi or the like is added has progressed well. But P
In the case of adding 10% of b, the embrittlement of the material was considerably advanced.

From these ingots, contact points were formed from arbitrary portions, and the incidence of restriking was investigated. Similar to the macrostructure of the ingot, those with less segregation had smaller variations, but those with less segregated contacts had larger variations.
In addition, a material to which Pb was added in a large amount could not obtain good electric characteristics.

[0038]

[Table 3] (Comparative Example 7, Examples 12, 13, 14, and Comparative Example 8) Mo powder having an average particle diameter of 5 μm and acid-free copper were dissolved, and
Melting and casting were performed under the same conditions as in Comparative Example 7 (Comparative Example 7).

Further, after enclosing Ar, 0.01% of B, 0.5% of Al, 2% of Ti, 3% of Y, and 15% of Zr were added. , 1
3, 14, Comparative Example 8).

From these ingots, a contact was made from an arbitrary part and the incidence of restriking was investigated. The re-ignition occurrence rate of a material to which a small amount of B, Ti, or the like was added tended to decrease. However, when the amount was too large, the electric conductivity significantly decreased.

[0041]

[Table 4] (Comparative Example 9, Examples 15, 16, 17, and 18) Cr and oxygen-free copper pulverized to an average particle diameter of 20 mm were melted in the same manner as in Example 1, filled with Ar, and then cast into a cast iron mold. (Comparative Example 9).

Similarly, casting was carried out in a mold made of Cu and a mold made of 1% Cr-Cu (Examples 15 and 16 respectively).

Further, casting was carried out in a vertically long mold so that the inner area became wider with respect to the volume (Example 17).

Further, the mold of Example 17 was cast into a mold having a plurality of through holes in the side surface (Example 18).

A cross-sectional macrostructure in the longitudinal direction of the ingot manufactured as described above was observed. In Comparative Example 9 cast into cast iron, weight segregation was remarkably observed, but Cu and C
In the ingot cast into the uCr alloy, a more uniform macrostructure was obtained, probably because the cooling rate was higher than that of cast iron.

A more uniform macrostructure was obtained in the case of casting into a vertically elongated Cu mold having a larger surface area. Was done. On the other hand, in the ingot in which many through holes were formed on the side surface of the vertically long Cu mold, the number of the aforementioned holes was small.

Processing was performed from any part of these materials, and the re-ignition evaluation was similarly performed. Although there is no significant difference in the frequency of restriking, it can be seen that the variation tends to decrease due to rapid cooling, indicating a favorable tendency.

[0048]

[Table 5] Not only in the above-described embodiment but also in other embodiments, the re-ignition frequency can be suppressed by combining the melting method, the form of the arc-resistant component material, the amount of the third element added, and the material shape of the mold. Obviously, the production of a homogeneous ingot can improve the material yield. In addition, it goes without saying that the present invention can be applied to other melting methods such as continuous casting.

Further, it is apparent that the ingot obtained by the present invention can be worked into a predetermined contact by taking into account any plastic working and heat treatment.

According to the present invention described above, it is possible to provide a contact material having excellent withstand voltage characteristics capable of suppressing occurrence of restriking with a high yield.

[0051]

According to the present invention, the performance of the method for producing a contact material for a vacuum valve can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vacuum valve to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a contact portion of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutoff room 2 Insulating container 3a, 3b Sealing fitting 4a, 4b Lid 5, 6 Conductive rod 7, 8 Electrode 9 Bellows 10, 11 Arc shield 13a, 13b Contact

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Atsushi Yamamoto 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant Co., Ltd.

Claims (9)

[Claims] A conductive component containing Cu, Cr, V,
A material obtained by melting a contact material containing an arc-resistant component containing at least one of W, Mo, Ta, Nb, and Fe within a range from the melting point of the conductive component to the melting point of the arc-resistant component, and then casting. A method for producing a contact material for a vacuum valve, comprising: 2. The method according to claim 1, wherein the conductive component is 40 to 90% by volume. 3. The arc-resistant component raw material has an average particle size of 1 μm to 10 m.
The method for producing a contact material for a vacuum valve according to claim 1, wherein the method comprises a powder or a granular material of m. 4. The method according to claim 1, wherein at least one of Bi, In, Sn, Te, and Pb is dissolved by adding 0.05 to 3% by volume. Manufacturing method of contact material for vacuum valve. 5. The method according to claim 1, wherein at least one of B, C, Ti, Zr, Y, and Al is added and dissolved in an amount of 0.01% by volume to 5% by volume. A method for producing the contact material for a vacuum valve as described above. 6. The method for manufacturing a contact material for a vacuum valve according to claim 1, wherein the mold is manufactured using at least one of Cu, Cu alloy, Fe, and Fe alloy. 7. The method according to claim 1, wherein the mold depth L is at least 1.5 times the mold diameter D. 8. The method for manufacturing a contact material for a vacuum valve according to claim 1, wherein a plurality of through holes are formed in a side surface of the mold. 9. The method for producing a contact material for a vacuum valve according to claim 1, wherein the melting method is a vacuum melting method or a continuous casting method.